Selective multi-modal transmission alteration

ABSTRACT

System and methods for an interface alteration device placed between a first segment and a second segment of a communication line of a vehicle. The interface alteration device identifies portions of an incoming data stream that are to be transmitted to a second interface alteration device and causes the identified portions to be transmitted to the second interface alteration device; identifies portions of the incoming data stream that are to be replaced by data received over a data link from the second interface alteration device; and generates an outgoing data stream that is a replicate of the incoming data stream except that the portions of the incoming data stream identified to be replaced are replaced with the corresponding data received from the second interface alteration device.

REFERENCE TO CROSS-RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/352,728 filed on Jan. 13, 2009, whichapplication is incorporated herein by reference in its entirety.

GOVERNMENT CONTRACT

The U.S. Government has a paid-up license in this invention and theright in limited circumstances to require the patent owner to licenseothers on reasonable terms as provided for by the terms of Contract No.W9124G-07-C-0006 awarded by the U.S. Army Aviation Technical TestCenter.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention generally relates to altering data in atransmission between network nodes. In particular, embodiments relate toenabling multiple modes of data transmission alteration based onrecognized conditions without the destination node being aware of theresulting altered transmission.

2. The Related Technology

In network communications, one problem is being able to alter data in acommunication line between nodes of a system without producing otherdetrimental effects. Detrimental effects can be any anomaly observedregarding the transmission state of the altered data as compared to thetransmission state of the original data that would be detectable by adestination node. For example, one problem that can occur when alteringdata in a communication line is introducing latency during thealteration process. Latency can potentially disrupt operation of a nodeor the system of nodes. Further, the latency requirement can bestringent for information that is used to synchronize events betweennodes. For example, consider the situation where synchronization iskeyed to a feature in the information, e.g., “synchronize on receipt ofthe last bit”, etc. Some systems experience latency by waiting for datato be transmitted to the data alteration device. Other systemsexperience latency due to buffering systems. Other detrimental effectscan include signals being received out of order, signals beingtransmitted at too high of transmission levels or too low oftransmission levels, and the like.

The subject matter claimed herein is not limited to embodiments thatsolve any disadvantages or that operate only in environments such asthose described above. Rather, this background is only provided toillustrate one exemplary technology area where some embodimentsdescribed herein may be practiced

BRIEF SUMMARY OF SOME EXAMPLE EMBODIMENTS

In general, example embodiments relate to systems and methods forperforming selective multi-modal transmission alterations. Inparticular, embodiments relate to enabling multiple modes of datatransmission alteration based on recognized conditions without thedestination node being aware of the resulting altered transmission.

One embodiment of the invention provides a system configured to beplaced between a first segment and a second segment of a communicationline, the communication line being placed between a first node and asecond node of a network, the system including a) a first portconfigured to receive incoming data from a first segment of acommunication line, the incoming data entering with a signal protocol,b) an interface alteration processor configured to identify conditionevaluation rules corresponding to the signal protocol, use the conditionevaluation rules to determine whether one or more predefined conditionsexists and which portions of the incoming data should be transmittedonto the second segment of the communication line as unaltered data oras altered data, for any portions of the alterable portion of theincoming data that should be transmitted as unaltered data, copyoriginal data of the incoming data corresponding to the unaltered dataportions, for any portions of the alterable portion of the incoming datathat should be transmitted as altered data, identify alteration rulesand generate altered data according to the alteration rules, anddetermine a transmission tolerance level based on at least one of thesignal protocol and/or a system-level protocol by which the altered dataand/or unaltered data should be transmitted onto the second segment ofthe communication line, and 3) a second port configured to transmit theunaltered data and/or altered data onto the second segment of thecommunication line to be delivered to the second node according to thetransmission tolerance level.

Another embodiment of the invention includes a method for altering datain a communication line between a first node and a second node, themethod including a) receiving incoming data from a first segment of acommunication line, the incoming data entering with a signal protocol,b) identifying condition evaluation rules corresponding to the signalprotocol to determine an evaluation portion of the incoming data, c)transmitting the evaluation portion of the incoming data onto a secondsegment of the communication line, d) while the evaluation portion isbeing transmitted, analyzing the evaluation portion to determine whetherone or more predefined conditions exist in the evaluation portion and todetermine whether an alterable portion of the incoming data exists, e)while the evaluation portion is being transmitted, determining whichportions of the alterable portion of the incoming data should betransmitted onto the second segment of the communication line asunaltered data or as altered data, f) for any portions of the alterableportion of the incoming data that should be transmitted as unaltereddata, copying original data of the incoming data corresponding to theunaltered data portions, and transmitting the copied data onto thesecond segment of the communication line, and g) for any portions of thealterable portion of the incoming data that should be transmitted asaltered data, identifying alteration rules, generating altered dataaccording to the alteration rules, and transmitting the altered dataonto the second segment of the communication line instead of originaldata of the incoming data corresponding to the altered data portions.

Yet another embodiment of the invention includes a method for alteringdata in a communication line between a first node and a second node, themethod including a) at an initial time, receiving incoming data from afirst segment of a communication line, the incoming data entering with asignal protocol, b) identifying an evaluation portion of the incomingdata based on the signal protocol, c) analyzing the evaluation portionto determine whether one or more predefined conditions exists andwhether an alterable portion of the incoming data exists, d) determiningwhich portions of the alterable portion of the incoming data should betransmitted onto the second segment of the communication line asunaltered data or as altered data, e) identifying a transmissiontolerance level associated with at least one of the signal protocoland/or a system-level protocol, f) transmitting the evaluation portionof the incoming data onto a second segment of the communication line, g)for any portions of the alterable portion of the incoming data thatshould be transmitted as unaltered data, copying original data of theincoming data corresponding to the unaltered data portions, andtransmitting the copied data onto the second segment of thecommunication line, h) for any portions of the alterable portion of theincoming data that should be transmitted as altered data, identifyingalteration rules, generating altered data according to the alterationrules, and transmitting the altered data onto the second segment of thecommunication line instead of original data of the incoming datacorresponding to the altered data portions, and i) wherein theevaluation portion, copied data and/or altered data are transmitted at apoint in time after the initial time that satisfies the transmissiontolerance level associated with the signal protocol and/or thesystem-level protocol.

Additional features of the invention will be set forth in thedescription which follows, and in part will be obvious from thedescription, or may be learned by the practice of the invention. Thefeatures of the invention may be realized and obtained by means of theinstruments and combinations particularly pointed out in the appendedclaims. These and other features of the present invention will becomemore fully apparent from the following description and appended claims,or may be learned by the practice of the invention as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other features of the presentinvention, a more particular description of the invention will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 illustrates an example of a network environment in whichinterface alteration devices incorporating features of the invention maybe implemented.

FIG. 2 illustrates an example of an interface alteration deviceincorporating features of the invention.

FIG. 3 illustrates an example of a timeline showing evaluation andalteration features of the present invention.

FIG. 4A illustrates an embodiment of a method for performing selectivemulti-modal transmission alteration incorporating features of theinvention.

FIG. 4B illustrates another embodiment of a method for performingselective multi-modal transmission alteration incorporating features ofthe invention.

FIG. 5 illustrates an example of an avionics system in which aninterface alteration device of the present invention may be implemented.

FIG. 6 illustrates an example of a remotely piloted vehicle system inwhich an interface alteration device of the present invention may beimplemented.

DETAILED DESCRIPTION

The principles of the embodiments described herein describe thestructure and operation of several examples used to illustrate thepresent invention. It should be understood that the drawings arediagrammatic and schematic representations of such example embodimentsand, accordingly, are not limiting of the scope of the presentinvention, nor are the drawings necessarily drawn to scale. Detaileddescription of well-known devices and processes have been excluded so asnot to obscure the discussion in details that would be known to one ofordinary skill in the art.

The present invention is broadly directed to altering data in acommunication line of a network. In particular, embodiments of theinvention selectively alter data in a communication line based onrecognized conditions without the destination node being aware that analteration has occurred. This includes minimizing any detrimentaleffects of the alteration, including latency, order of transmission, andtransmission levels. Furthermore, the present invention allowsalteration of data to occur in various modes. The invention alsopreserves the integrity of information that is passed through networksystem without being altered. In addition, the present inventionprovides for scalability to multiple communication lines as well asmultiple transmission protocols.

FIG. 1 illustrates one exemplary environment in which the features ofthe invention can be practiced. FIG. 1 illustrates a network 100 showinga system 102 having one or more buses 104 a-c. Each bus 104 a-c isconnected to a processing terminal, referenced as terminals 106 a-d.Further, one or more processing terminals 108 a-d may be networked inthe system 102 without being connected directly to a bus. Buses 104 a-c,terminals 106 a-d, and terminals 108 a-d are thus exemplary of nodes ofa system 102. An interface alteration device 110 is inserted into one ormore communication lines in the system 102 to break the communicationlines into two segments that can then be handled in isolation. Theinterface alteration device 110 can break communication lines at anylocation in system 102. Furthermore, interface alteration device 110 isscalable in that it includes data interfaces that allow breaks in asmany communication lines as needed control the state of the system 102.

As used herein, the term “communication line” refers to any means forallowing information or data to be transmitted to and/or from nodes in asystem. As such, a line is used diagrammatically to illustrate thatcommunication can occur between system nodes. However, the use of asolid line is used by way of illustration and not by way of limitation.The communication line can be any physical or wireless connection usedto transmit data. “Data,” “information,” or “instructions” can betransmitted on the communication line as “signals.” These terms may beused interchangeably herein to refer to any data that can be carried inthe communication line, which can be transmitted in the form of, but notlimited to, electrical signals, optical signals, acoustic signals,pressure signals, radio signals, carrier wave signals, pneumaticsignals, and the like, depending on the transmission medium of thecommunication line. Furthermore, the communication line can carrysignals using various formats, such as continuous analog, digital,discrete, matrixed, multiplexed, and the like, depending on thetransmission medium.

Generally, the signals will be transmitted according to a “protocol”which enables both transmitting node and receiving node to communicate.For signals formatted in digital format, protocol generally defineserror checking methods, data compression methods, how the transmittingnode will signal data transmission completion, how the receiving nodewill acknowledge receipt of the data, and the like. For signals in acontinuous analog format, the protocol could define ranges of voltageand current values and transmission bandwidth (e.g., 1 Hz, 10 kHz, 1.5GHz). Those of skill in the art will appreciate that other protocols canbe identified and/or determined based on the signaling format.

FIG. 1 illustrates that the interface alteration device 110 can beconnected to more than one communication line, although in someembodiments, the interface alteration device 110 can be placed in asingle communication line. The interface alteration device 110 may breakone or many communication lines in parallel at the same time. Asdescribed further below, the interface alteration device 110 may itselfbe isolated from the communication line using a set of relays used toinsert or remove the interface alteration device 110 from thecommunication line; these relays can be controlled from the interfacealteration device 110 or an alternate external source.

The data received from a segment can be selectively altered before beingsent on the other segment, based on 1) condition evaluation rulescontaining instructions on how to evaluate incoming data to determinewhether one or more predefined conditions exists and determine whichportions of the incoming data should be transmitted onto the secondsegment of the communication line as unaltered data or as altered dataand 2) alteration rules which contain instructions on how to alter thedata; both of which can be stored locally or could be received remotelyfrom an external source. FIG. 1 shows that in one embodiment, theinterface alteration device 110 can communicate with an external source112 in order to receive condition evaluation rules and/or alterationrules. In one embodiment, information can be pushed/pulled to and/orfrom the external source 112 in real time, or can be transmitted on ascheduled basis, or as needed. As used herein, the term “externalsource” refers to a network or system which communicates with theinterface alteration device to provide condition evaluation rules,alteration rules, and/or transmission tolerance levels and does notcommunicate with other nodes of the system 102. It will be appreciatedthat the system 102 would otherwise be operational without the interfacealteration device 110 and/or external source 112.

For illustrative purposes, the flow of data alteration will be describedwith respect to communication line 120. The interface alteration device110 breaks communication line 120 into two isolated segments 120 a and120 b, as shown in FIG. 1. In this example, the interface alterationdevice 110 is analyzing data that is flowing in the direction indicatedby the arrows. Thus, without interface alteration device 110, the datawould flow directly from bus 104 a (the source node) to terminal 108 b(the destination node). Incoming data received from the first segment120 a from the source node is analyzed by the interface alterationdevice 110 using condition evaluation rules to determine whether one ormore predefined conditions indicate that the incoming data should bealtered. If so, the interface alteration device 110 alters the incomingdata according to alteration rules to generate altered data. Theinterface alteration device 110 then transmits the altered data and/orunaltered data on the second segment 120 b to the destination node basedon transmission tolerance levels to minimize detrimental effects,described further below, such that the destination node is not able todetect that the altered data was in fact altered from the original data.Existing nodes using the communication line are unaware that thecommunication line has been broken and unaware that data has beenaltered from its original state. Altering the signal allows a user tothus alter the operating state of nodes of the system.

It will be appreciated that each communication line will generally beable to allow bi-directional communication and that the uni-directionalflow of data from bus 104 a to terminal 108 b is provided only todescribe features of the invention. In the situation where communicationlines allow bi-directional data flow, it is conceivable that eachsegment could be carrying original data and also altered data in eitherdirection.

The interface alteration device can intelligently operate in multiplemodes, which modes are not mutually exclusive of each other and canoperate concurrently. The interface alteration device 110 may pass datathrough without alteration (“pass-through mode”); may pass some dataunaltered while altering other data (“over-drive mode”); or may use onesegment to transmit and/or receive information to/from a node even whenthe node is offline, inactive, or otherwise not present on the segment(“emulation mode”).

Turning to FIG. 2, the interface alteration device 110 is shown infurther detail, indicated by reference numeral 200. As discussed above,a communication line 202 can be broken by the interface alterationdevice 200 into a first segment 202 a and a second segment 202 b, whichboth make up original communication line 202. FIG. 2 illustrates thatthe first segment 202 a and second segment 202 b are communicating withsome aspect of system 102 shown in FIG. 1. The actual placement ofinterface alteration device 200 will depend on the protocol of thesystem in which it is placed. The communication line 202 allowsbi-directional communication. Interface alteration device 200 has afirst port 204 a that connects to first segment 202 a of communicationline 202. Likewise, a second port 204 b is provided that connects tosecond segment 202 b of communication line 202.

Interface alteration device 200 can be connected directly to segments202 a and 202 b of communication line 202. However, in anotherembodiment (shown in FIG. 2), interface alteration device 200 can beinserted into an original communication line 202 using a set of relays206 a, 206 b, 206 c appropriate to the transmission media of thecommunication line 202. These relays 206 a-c can be used to assureremoval of the interface alteration device 200 from the communicationline 202 if necessary, for example due to safety or similarconsiderations. When the interface alteration device 200 is online, therelay 206 a is taken offline and relays 206 b and 206 c are placedinline so that the data flow is forced through interface alterationdevice 200. When the relay 206 a is offline, those of skill in the artwill appreciate that relay 206 a will provide termination.

In operation, the interface alteration device 200 receives original dataon segments 202 a, 202 b of the communication line 202. In addition, asdescribed further below, interface alteration device 200 recognizeswhether certain predefined conditions exist based on conditionevaluation rules, and, as appropriate, alters certain portions of thedata based on alteration rules. Transmission tolerance levels can alsodefine how transmission of data is to be performed so that thedestination node will be unaware that alteration has occurred to thedata stream. The interface alteration device 200 also transmits theoutgoing original data and/or altered data on the opposing segment 202 aor 202 b. Further, the interface alteration device 200 receives anddistributes information through the external interface 208. Each ofthese functions is further described as follows.

Interface alteration device 200 includes signal transceivers 216 a, 216b connected to each port 204 a, 204 b, respectively. Each signaltransceivers 216 a, 216 b includes a differential receiver 210 a, 210 b,a line driver 212 a, 212 b, and a transceiver control 214 a, 214 b,respectively. The signal transceivers 216 a, 216 b transmit and/orreceive signals from segments 202 a, 202 b and convert signals from theoriginal transmission media into signals that can be operated on withinthe interface alteration device 200. Further, the alteration processor218 identifies outgoing signals intended to be transmitted through thesegments 202 a, 202 b and converts the outgoing signals back into theoriginal signal format to be sent by the appropriate transceiver 216 a,216 b to the opposite segment 202 a, 202 b. The transceivers 216 a, 216b may be of any suitable type for the original signal protocol and thealteration processor 218. For example, the transceivers 216 a, 216 b canbe any suitable mix of electrical hardware, opto-electronic hardware,mechanical hardware, wireless hardware, vibration hardware, hydraulichardware, acoustic hardware, and the like.

Alteration processor 218 uses condition evaluation rules to identifypredefined conditions in which altered data needs to be generated andperforms the desired alteration of data using alteration rules. Thealteration processor 218 can include hardware such as aField-Programmable Gate Array (FPGA), or any other Programmable LogicDevice (PLD) acceptable and useful for implementing selectivetransmission alterations of the present invention in a special-purposeprocessor. Preferably, the hardware and/or software used to implementthe alteration processor 218 is software programmable, able to handleserial and/or parallel interfaces, and have access to storage eitherinternally in the chip or be able to access other storage. For example,one product that can produce programmable logic is the XILINX® FPGAchip. Additionally, the alteration can be implemented in ageneral-purpose processor if the through-put of the processor issufficient. In one embodiment, when data comes in through transceivers216 a, 216 b the incoming signals are processed by the alterationprocessor 218 by receiving incoming original data from one side of acommunication line (e.g., segment 202 a), accessing condition evaluationrules to determine whether the original data should be altered, usingalteration rules to alter the original data to generate altered data,and transmitting the altered data to the other side of the communicationline (e.g., segment 202 b) according to transmission tolerance levels.In one embodiment, the interface alteration device 200 may determinethat the original data does not need to be altered at all.

In another embodiment, a source node of the communication line may beidle or offline. The interface alteration device 200 may determine thatdata needs to be generated and transmitted on an outgoing segment of acommunication line (e.g., segment 202 b) to another destination node inorder to influence the operation or state of the node. Note that in thisembodiment, the term “original data” refers to the fact that only idledata or null data could be flowing to the destination node, so that theaddition and/or modification of data on the communication line by theinterface alteration device results in altered data. The modes in whichthe interface alteration device 200 can operate will be described infurther detail below.

The controller 220 configures the alteration processor 218 according tocondition evaluation rules 222 of the user received via the externalinterface 208. Thus, the controller 220 may store condition evaluationrules 222 in storage 223 located on the device 200. The controller 220also receives, stores, and/or routes alteration rules 224 from theexternal interface 208. For example, the alteration rules 224 can bereceived from the external interface 208 and routed by the controller220 to the alteration processor 218 for making alterations in the datastream when operating in the over-drive and emulation modes. Thus,interface alteration device 200 can include a third port 204 c such thatthe controller 220 can receive from an external interface 208 thecondition evaluation rules indicating predefined conditions to searchfor in the incoming data and portions of data that should be unalteredor altered, and/or the alteration rules used to alter the original data.

The controller 220 also communicates with external interface 208 totransmit and/or receive data to and/or from an external source via port204 c. The external interface 208 can incorporate any interface suitableto the function of the controller 220 and the external source.

Having described the components of the interface alteration device 200,the various modes in which the device 200 can operate will now bedescribed in further detail. Generally, interface alteration device 200can operate in pass-through mode; overdrive mode; and emulation mode.

When operating in pass-through mode, the alteration processor 218receives an original signal (from segment 202 a or 202 b received viaeither transceiver 216 a or 216 b) from a receiving transceiver anddetermines whether the signals should be handled in pass-through mode.If so, the alteration processor 218 causes the transmitting transceiverto reproduce the signal to be transmitted by the opposite transceiver.

When operating in over-drive mode, the alteration processor 218 willalter at least a portion of the original signal based on conditionevaluation rules and/or alteration rules. The alteration processor 218receives an original signal (from segment 202 a or 202 b received viaeither transceiver 216 a or 216 b) and evaluates the original signalusing condition evaluation rules to determine whether the originalsignal needs to be altered. If so, the alteration processor 218 altersthe original signal using alteration rules. The alteration processor 218transmits the altered data to the opposite transceiver from which theoriginal signal arrived. The altering function may be desired onlyduring a particular segment of time; in this case the alterationprocessor 218 recognizes predefined conditions when the alteringfunction should be initiated.

When operating in emulation mode, the alteration processor 218 bases theemulation function on receipt of idle or null data as original data.Alteration processor 218 generates information to one or both segments202 a, 202 b of a communication line based on condition evaluation rulesand/or alteration rules. For example, the interface alteration device200 may be registering idle data on a communication line and addsaltered data to a segment of the communication line without havingchanged original incoming data.

Thus, as used herein, the term “original data” can include any data thatis being analyzed by the interface alteration device. The term“condition evaluation rules” refers to one or more predefined conditionsthat the interface alteration device looks for in incoming data. Forexample, a predefined condition could be to identify a header elementwith a known bit pattern in a digital signal. Once the known bit patternis identified, the condition evaluation rules may have rules thatspecify certain portions of the incoming data to be altered orunaltered. In another embodiment, a predefined condition could be avoltage level, current level, and/or bandwidth level of a continuousanalog signal. Other examples are readily ascertainable based on theteachings herein.

The term “alteration rules” refers to how the data is to be altered,including any actual data that is used to add data to, delete data from,replace data, modify data, or otherwise change original data to form“altered data.” “Altered data” that is thus generated can be all newdata, or could be derived from the original data. “Altered data” canalso refer to adding active data when the original incoming data is idledata or null data. Alteration rules also includes instructions orformulaic data that analyzes conditions such as the original data,history of the original data or any other condition present in theoriginal data and/or signal protocol, and can algorithmically determinehow to generate the altered data. Another example of use of conditionevaluation rules could be using a matched filter to detect theconditions. Alteration rules would then include causing the signal tomatch a predefined pattern.

Condition evaluation rules and/or alteration rules can be received fromthe external source for storage at the interface alteration device, orcan be used in a “just-in-time delivery mechanism” that meets the timingrequirements of a transmission tolerance level associated with theappropriate signal protocol and/or system-level protocol (discussedbelow); or the condition evaluation rules and/or alteration rules can bealready buffered, pre-programmed within the interface alteration device,or otherwise already locally stored at the time ofevaluation/alteration.

Finally, an additional function of the alteration processor 218 is toidentify when information received via either transceiver 216 a, 216 bshould be passed to the controller 220 for distribution to the externalsource via external interface 208.

One aspect of the invention in any mode in which the interfacealteration device 200 operates is to ensure that the outgoingtransmissions from the device 200 do not cause detrimental effects. Asmentioned above, detrimental effects can include, but are not limitedto, latency in the original transmission, order of transmission,transmission characteristics, and the like. The “transmission tolerancelevel” can thus be derived from the signal protocol itself, and/or fromsystem-level protocols not derivable from the signal protocol, such as,but not limited to, applications operating on system components, thecapabilities of the system components, and the like. In one embodiment,the interface alteration device 200 can determine which of the signalprotocol and/or system-level protocols defines the most stringentlimitations and perform the transmission based on the most stringentprotocol.

In one example, the transmission tolerance level may define the totaldelay that can be allowed in receiving, processing, and re-transmittinga signal by evaluating the signal protocol of the original signal, plusany limitations imposed by the other nodes on the original communicationline, which collectively contribute in this example to the transmissiontolerance level. In this example, the transmission tolerance leveldefines a set of time limits within which the interface alterationdevice 200 must operate to remain undetected when altering informationmoving to or from nodes or systems on the communication line 202. Inaddition to the signal protocol, system-level protocols may be enforcedby other nodes or systems on the communication line; these limits mayalso need to be satisfied. The transmission tolerance level maytherefore define a timing requirement by which original and/or altereddata must be transmitted from the interface alteration device.

Further, for multi-packet transmissions, the “transmission tolerancelevel” may define an order of transmission. In some cases, this couldresult in some of the original and/or altered data being buffered for aperiod of time.

In addition, “transmission tolerance levels” may define acceptabletransmission characteristics or levels. For a continuous analog signal,the signal protocol may require that the signal be within prescribedvoltage limits, current limits, and/or a minimum bandwidth. Thus, atransmission tolerance level may be defined where the voltage of theoutgoing signal may need to be reduced and/or increased to the requiredrange of voltage. For example, the voltage limit may not be able toexceed 2.3 volts; where a signal exceeding 2.3 volts could cause adetrimental effect. So, in this example, if the signal exceeds 2.3volts, the transmission tolerance level could require the transmissionto be limited to 2.3 volts.

Importantly, the transmission tolerance level helps define timing,transmission orders, and/or signal characteristics which result in thedestination node being unaware that the data stream has been analyzedand/or altered.

FIG. 3 illustrates one example of how the transmission tolerance levelscould affect data alteration to occur without generating detrimentaleffects, such as latency. The example is described using MIL-STD-1553protocol (hereinafter referred to as the “1553 protocol”). However, itwill be appreciated that the broad teachings may apply to any otherprotocol to be able to implement the present invention and obtainsimilar advantages.

Generally, the 1553 protocol operates by having a bus controller issue acommand, followed by one or more data words. When the command/data wordsare received by a destination node, the destination node issues a statusword to acknowledge receipt of the command/data word. FIG. 3 illustratesoriginal data 300 that is being received at T₀=0 μs by the receivingtransceiver of the interface alteration device.

In the example of FIG. 3, when the receiving transceiver receives data,the transmitting transceiver retransmits the data substantially inreal-time onto the outgoing segment of the communication line, shown astransmitted data 300′. For example, the transmitting transceiver cantransmit at 9,600 Hz baud. This retransmission is shown in FIG. 3, inwhich the transmitting transceiver retransmits the first bit of theoriginal data 300 a time T_(lag) after the first bit is received by thereceiving transceiver. In one embodiment, the interface alterationdevice has hardware and software that enables the transmittingtransceiver to retransmit data received by the receiving transceiverfaster than the timing requirements imposed by the transmissiontolerance level defined by the incoming protocol. For example, in oneembodiment, the transmitting transceiver can replicate and transmit theincoming data 0.4 μs after the original data arrives at the receivingtransceiver. If the 1553 protocol requires that transmission be receivedwithin +/−1 μs time limitation, the 0.4 μs lag created by the interfacealteration device falls well within required time limits. The 0.4 μs lagis shown by way of example only. Note that FIG. 3 is not drawn to scale.Thus, while the interface alteration device could generate some amountof lag, such would not be a detrimental affect as long as it met thetransmission tolerance level requirements.

FIG. 3 also illustrates that, in one embodiment, the transmittingtransceiver retransmits the original data and/or altered data (indicatedby altered bits 320) substantially in real-time. FIG. 3 illustrates thesituation where altered data is generated and transmitted by thetransmitting transceiver. However, the pass-through mode would looksubstantially similar to FIG. 3 except the altered bits 320 wouldinstead be original data that was received, copied and retransmitted bythe transmitting transceiver.

The following description will now describe how alteration occurs in the“over-drive” mode, using the 1553 protocol as an example. FIG. 3 showsoriginal data 300 having a command word portion 302 and a data wordportion 304. In this example, only one data word is shown. For the 1553protocol, the data length is 20 bits for the command word portion 302and 20 bits for the data word portion 304. Naturally, other protocolsmay have data of varying lengths. The 1553 protocol transfers at 1 MB/s,so the original data shown transmits at approximately 1 bit per/μs.

The interface alteration device uses condition evaluation rules toanalyze an “evaluation portion”, referred to by 306. As used herein, theterm “evaluation portion” generally refers to beginning portions of theoriginal data that the interface alteration device compares to thecondition evaluation rules to assess whether or not one or morepredefined conditions exist to engage the alteration functions of thepresent invention. In the example of FIG. 3, the region formed by bit 1to 23 is the evaluation portion 306. However, the evaluation portioncould be smaller or larger as needed by the condition evaluation rulesto make the determination of whether original data needs to be alteredand to provide enough time for the alteration to occur.

In the example of FIG. 3, by bit 14, the interface alteration device hasread the command word, the destination address, the transmit/receivebit, and sub address defined in the command word portion 302. By thistime, the interface alteration device has enough information to be ableto determine whether the signal is a command as opposed to a status andwhether data may need to be altered. In the example of FIG. 3, theinterface alteration device can also determine the word count found inbits 15 through 19. In the example of FIG. 3, the interface alterationdevice has used the evaluation portion to determine an “alterableportion” 312 of original data 300. The “alterable portion” includes datathat can be overdriven by the interface alteration device.

In the example of FIG. 3, a parity bit 20 and three synch bits 21through 23 provide a sufficient amount of time (4 μs) to decide whetherto alter any portion of the alterable portion 312. For 1553 protocol, 4μs is sufficient for an FPGA or finite state machine to make a decisionand then implement any overdriving function, including accessing anyalteration rules to perform the overdrive function.

The alterable portion 312 of incoming data 300 is then received by thereceiving transceiver. In the example of FIG. 3, the alterable portionincludes 16 data bits (bits 24 through bits 39) and one parity bit (bit40). The original data in each bit will be copied and transmitted by thetransmitting transceiver unless an alteration is made to a bit. If analteration is made to the bit, the interface alteration deviceidentifies alteration rules and makes the alteration accordingly. Thealtered data is then transmitted onto the outgoing segment by thetransmitting transceiver.

In the example of FIG. 3, note that the interface alteration device istransmitting substantially simultaneously as it is being received, anddoes not need to store or buffer the incoming data. So, in the exampleof FIG. 3, by 40.04 μs from when the original data 300 was firstreceived by the receiving transceiver, all of the transmitted data 300′has been transmitted onto the outgoing segment of the communicationline. The transmitted data 300′ is similar to the original data 300except that bits 25, 28 and 37 of transmitted data 300′ are altered bits320, while all the rest are copies of the original data. Note that inthis case the changes to bits 25, 28, and 37 did not require a change inthe parity bit 40. Thus, like the original data, in this example, thetransmitted data 300′ has a command word (referred to as 302′) and adata word (referred to as 304′).

Further, because the latency falls well below time limits of theprotocol, the destination node will receive the transmitted data 300′within transmission tolerance levels. Furthermore, the destination nodewill not be able to detect that the transmitted data 300′ was alteredduring transmission and will proceed to process the transmitted data300′ accordingly.

Although not shown, it will be appreciated that the interface alterationdevice can log the command word, data word, and/or any status indicatorsreceived remotely to the external source at any time after it isreceived by the receiving transceiver. Because logging can occursubstantially in real-time with receipt of the incoming data, during theevaluation portion 306, an external source could be analyzing theincoming data, generating or accessing alteration rules, andtransmitting alteration rules to the interface alteration device. In oneembodiment, the alteration rules is received by the interface alterationdevice just prior to when the transmitting transceiver is going totransmit the particular data portion that is going to be overdriven,which allows the interface alteration device to make a “just in time”alteration of the data before it is transmitted.

While most examples herein will describe adding or modifying theoriginal data and retransmitting a modified data portion, “alteration”broadly includes any way of modifying the original data including, butnot limited to, adding data, replacing data, modifying data, deletingdata, or even refusing to transmit data. Alteration could thus be usedto terminate a data transmission by altering the number of bits that aretransmitted or some other way such that the destination node willinvalidate it or refuse to acknowledge the signal. Altering can thusinclude deleting or refusing to transmit original data so that thedestination node does not receive the entire original data, which willbe inherently rejected by the protocol.

The scenario shown in FIG. 3 is provided as an example only and otherdesign configuration for defining the evaluation portion, usingcondition evaluation rules, defining an alterable portion, usingalteration rules, and using transmission tolerance levels arediscernable once the signal protocol and/or system-level protocols areknown. For example, the above teachings can be applied to other datatransmit protocols such as, but not limited to, Ethernet, Carrier SenseMultiple Access (CSMA), Time Division Multiple Access (TDMA), ARINC 429,continuous analog, RS-232 and RS-422 and similar serial protocols,Universal Serial Bus, discrete signals (which remain in one state for along time compared to the state transition time), and the like. In oneexample, the above features could be implemented for a continuous analogsignal in which the condition evaluation rules dictate searching for aparticular range of transmission level of the original signal (e.g.,between −5 to +5 volts). When the defined condition is identified, thealteration rules could instruct the transmitting transceiver to transmitthe signal 2× the original signal. Furthermore, the transmissiontolerance levels could have a signal protocol limit of +15 volts, so anytransmission that exceeds this limit is trimmed to +15 volts. This is anexample of selective transmission alteration in which the alterationoccurs for when a particular condition is found, and may or may notapply to the entire signal. Further, this is an example of atransmission tolerance level that does not necessarily rely on timingrequirements.

Turning to FIGS. 4A and 4B, exemplary methods will be described. FIG. 4Adescribes a method in which the evaluation function and alterationfunctions overlap. In one embodiment, the incoming data and outgoingdata can be transmitted substantially in real-time while still enablingthe alteration functions of the present invention.

At 402, the receiving transceiver receives incoming data from a firstsegment of a communication line. The incoming data enters with a signalprotocol that allows the interface alteration device to determinecondition evaluation rules, alteration rules, and/or transmissiontolerance levels.

At 404, the alteration processor identifies condition evaluation rulesto determine an evaluation portion of the incoming data based on thesignal protocol. At 406, the transmitting transceiver beginstransmitting the evaluation portion of the incoming data onto a secondsegment of the communication line.

At 408, the alteration processor analyzes the evaluation portion todetermine whether an alterable portion of the incoming data exists. At410, the alteration processor uses condition evaluation rules todetermine which portions of the alterable portion should be transmittedas unaltered data or altered data.

At 412, the alteration processor determines whether the alterableportion should be transmitted as altered data or unaltered data. If datain the alterable portion should be transmitted as altered, at 414, thealteration processor identifies alteration rules and generates altereddata according to the alteration rules. At 416, the transmittingtransceiver transmits the altered data onto the second segment of thecommunication line instead of original data of the incoming datacorresponding to the altered data portions.

If the data in the alterable portion should be transmitted as unaltered,at 418, the transmitting transceiver copies original data of theincoming data corresponding to the unaltered portion. At 420, thetransmitting transceiver transmits the copied data onto the secondsegment of the communication line.

FIG. 4B illustrates another embodiment of a method of the invention inwhich the transmission tolerance level do not require the evaluation andtransmission of the data stream to overlap. In FIG. 4B, at 452, at aninitial time, the receiving transceiver receives incoming data from thefirst segment of the communication line, the incoming data entering witha signal protocol. At 454, the alteration processor identifies conditionevaluation rules to determine an evaluation portion of the incoming databased on the signal protocol. At 456, the alteration processor analyzesthe evaluation portion to determine whether an alterable portion of theincoming data exists. At 458, the alteration processor uses conditionevaluation rules to determine which portions of the alterable portionshould be transmitted as unaltered data or altered data. At 460, thealteration processor identifies a transmission tolerance levelassociated with the signal protocol and/or system-level protocols.

At 462, the transmitting transceiver transmits the evaluation portion ofthe incoming data onto a communication line at a point in time after theinitial time such that transmission of the evaluation portion satisfiedthe transmission tolerance level requirements. At 464, the alterationprocessor uses condition evaluation rules to determine which portions ofthe alterable portion should be transmitted as unaltered data or altereddata. If data in the alterable portion should be transmitted as altered,at 466, the alteration processor identifies alteration rules andgenerates altered data according to the alteration rules. At 468, thetransmitting transceiver transmits the altered data onto the secondsegment of the communication line instead of original data of theincoming data corresponding to the altered data portions. If the data inthe alterable portion should be transmitted as unaltered, at 470, thetransmitting transceiver copies original data of the incoming datacorresponding to the unaltered portion. At 472, the transmittingtransceiver transmits the copied data onto the second segment of thecommunication line.

FIGS. 4A and 4B are only two examples of methods that could beimplemented according to the teachings of the present invention.

While protocols having serial transmissions have been described in theexamples, it will be appreciated that the above teachings and methodscan also apply to other protocols, including multi-packet transmissions.Various protocols, such as Ethernet, exist which send data in the formof multiple packets that must be reassembled in order to ascertain theentire message. Most multi-packet protocols include algorithms whichdefine probabilities for a packet successfully being delivered to theintended destination. Thus, the present invention can ascertain atransmission tolerance level from the signal protocol and/orsystem-level protocol to determine transmission limits for multi-packettransmissions. Generally, since these multi-packet protocols account forpackets being sent out of order, lost data packets, collisions, etc.,and the present invention does not rely on whether data is received in acertain order, the present invention can still apply to multi-packettransmissions.

The transmission tolerance level can be ascertained from the signalprotocol and/or system-level protocols. For multi-packet configurations,the alterable data may be ascertained from the first packet that isreceived by evaluating the packet header information, even if the firstpacket arrives out of order from the packet grouping. Thus, at least aportion of the packet header could be an “evaluation portion” forpurpose of the present invention. In another example, an XML file sentbefore or with data packets can form the evaluation portion. Otherprotocols tag data which can serve as the evaluation portion. Theinterface alteration device can evaluate the packet, determine whetheror not any of the packet data needs to be altered and transmit thepacket onto it destination. The interface alteration device can thenwait for the other packets in the group to arrive and make changes asthey arrive. Or, alternatively, some protocols, will allow the interfacealteration device to buffer all data packets in a group and thentransmit the group together with any alterations as long as it meets thetransmission tolerance level requirements.

Because most multi-packet protocols do not rely on the packets beingreceived in a particular order, and since the present invention couldtransmit data either serially and/or reordered, multi-packet data canfall under one of the two methods described in FIGS. 4A and 4B or anyother method that could be conceived based on the teachings of thepresent invention. The present invention is thus based on the premisethat as long as the destination node receives the entire message withinthe probability defined by the protocol, the interface alteration devicecan serve to perform valuable data alteration without interrupting thesystem processes. For example, if a protocol has an end-to-end timing bywhich all packets in a message need to be received, the presentinvention can transmit those data packets in any order and so long as itsatisfies the transmission tolerance level timing requirement.

The interface alteration device can be built as an integrated piece intoa large complex system that can be used in all phases of testing,simulation, and live commercial phases. Or, can be built as a modularunit that can conform to form factor standards (such as avionic) suchthat it can be sold off-the-shelf. Once the teachings of the presentinvention are understood, the applications of the invention arelimitless. A few examples are appropriate.

One potential use of the present invention is to modify flight controlsfor a piloted aircraft. FIG. 5 illustrates one embodiment of how thiscan be implemented. Many of the elements of FIG. 5 are known to those ofskill in the art, so will not be described in detail here. FIG. 5depicts aircraft controls 502 having a bus that operates using a 1553protocol, shown by the heavy dashed lines 508. The interface alterationdevice 504 breaks the bus communication line using the combinationT-cable and bus relay. The interface alteration device 504 enablesalteration of data occurring in the communication line that, withoutdevice 504, would normally come from the control display navigation unit(CDNU—shown as the control & display and the mission computer). Theinterface alteration device would be able to communicate with anexternal source 506 via terrestrial and/or aerial means, such asbroadcast towers and/or satellites which can transmit and/or receivedata to and/or from the interface alteration device.

In this embodiment, the source node for data transmissions on thecommunication line could be the CDNU while the destination node could bethe flight control system, sensors, actuators, and/or vector graphicsdevice. The alteration processor routes commands in either a passthrough mode or overdrive mode, shown by solid lines 510. The alterationprocessor can also route altered data as shown by the light dashed lines512. Furthermore, the alteration processor could route emulation datawithout data being required to have been received from the incomingtransceiver. While not shown, it will be appreciated that the alterationprocessor is a combination of hardware and/or software that enables thealteration functions of the present invention.

In another embodiment, the interface alteration device is able tocommunicate with a crew station interface (CSI) to allow a humanoperator to interact with the system as follows.

During operation, the pilot in the cockpit will not be able to discern adifference between normal flight operations and altered flightoperations generated by the interface alteration device since the dataalterations will comply with transmission tolerance levels. So, theaircraft would be able to experience fully piloted commands, acombination of piloted commands and altered commands from the externalsource, or fully altered commands from the external source. In oneexample, the interface alteration device can enhance the safety of anaircraft by being able to test flight conditions and being able toactually remotely control the operation of the aircraft.

The avionics example of FIG. 5 is provided by way of example only. Theinvention could be applied to any manned vehicle. Thus, in one exemplaryimplementation, the present invention can be applied to an avionicssystem in which the interface alteration device can be used to simulatea flying or grounded, partial, or complete aviation electronics systeminto arbitrary states as defined by the avionics interfaces. The presentinvention could also be applied to autonomous control of a mannedvehicle to selectively remove some or all information transfers from anode or system and redirect them to other local or external systems toenable autonomous control of the manned vehicle.

FIG. 6 shows another application which allows for a completelyautonomous vehicle. FIG. 6 shows a remotely piloted vehicle 602 and aproxy vehicle 604. Both the remotely piloted vehicle 602 and the proxyvehicle 604 have controls 606, 612 and vehicle systems 608, 614,respectively. The pilot 618 is able to sit at the proxy vehicle 604 andmanipulate the controls 612 and at the proxy vehicle as if the pilotwere sitting in the remotely piloted vehicle 602 itself.

An interface alteration device 610, 616 sits at both the remotelypiloted vehicle 602 and the proxy vehicle 604, respectively, between thecontrols and vehicle system. A data link 620 is generated between thetwo interface alteration devices 610, 616 so that the proxy vehicle 604can generate emulation data to be transmitted to the remotely pilotedvehicle 602. Further, interface alteration device 610 at the remotelypiloted vehicle 602 would capture system data from the remotely pilotedvehicle to be transmitted to the proxy vehicle 604 so that the proxyvehicle can react to actual flight conditions.

For example, a fly-by-wire aircraft can be used as a proxy groundstation for a remotely piloted aircraft. On the proxy aircraft theinterface alteration device is connected between the pilot's controlsand the flight control computer and/or any internal communicationchannels as necessary for the level of control desired. Anotherinterface alteration device is connected similarly in the remoteaircraft. The two interface alteration devices communicate by means of adatalink or similar communication channel. Control inputs on the proxyground station are monitored by the interface alteration device andtransmitted to the remote aircraft. The remote aircraft's interfacealteration device receives the signals form the proxy ground station andmanipulates the controls on the remote aircraft accordingly. In asimilar fashion, data is monitored and sent to the proxy ground stationas needed to provide the ground station systems and pilot sufficientdata to remotely pilot the aircraft. Data is manipulated in the proxyground station to keep the proxy aircraft stationary while providingfeedback to the pilot. Data is manipulated in the remote aircraft toignore the local controls and use the remotely generated instructions.

This application is not limited to a stationary proxy; it can also beused to slave other operator-less systems to a single manned system.Delay or other more advanced logic can be applied to adapt the slavesystem or systems into a convoy.

The proxy control does not have to be manned. This application can beused for any partially or fully autonomous system to remotely controlone to N other systems.

Those of skill in the art will appreciate the great commercial andeconomical advantages to being able to modify piloted controls and/or togenerate a completely autonomous aircraft.

Furthermore, those of skill in the art will appreciate that theinterface alteration process and system can be applied to anyinformation transmission protocol to alter any system that reachesstates based on information received through a signaling interface. Theconcepts of the present invention can be applied to other communicationstandards on any transmission medium including optical fiber, Ethernet,Carrier Sense Multiple Access (CSMA), Time Division Multiple Access(TDMA), ARINC 429, continuous analog, RS-232 and RS-422 and similarserial protocols, Universal Serial Bus, discrete signals (which remainin one state for a long time compared to the state transition time), andthe like. The signals can be any medium—optical, electrical, carrierwave, pneumatic, pressure, acoustic, radio, and the like.

Embodiments include general-purpose and/or special-purpose devices orsystems that include both hardware and/or software components.Embodiments may also include physical computer-readable media and/orintangible computer-readable media for carrying or havingcomputer-executable instructions, data structures, and/or data signalsstored thereon. Such physical computer-readable media and/or intangiblecomputer-readable media can be any available media that can be accessedby a general purpose or special purpose computer. By way of example, andnot limitation, such physical computer-readable media can include RAM,ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storageor other magnetic storage devices, other semiconductor storage media, orany other physical medium which can be used to store desired data in theform of computer-executable instructions, data structures and/or datasignals, and which can be accessed by a general purpose or specialpurpose computer. Within a general purpose or special purpose computer,intangible computer-readable media can include electromagnetic means forconveying a data signal from one part of the computer to another, suchas through circuitry residing in the computer.

When information is transferred or provided over a network or anothercommunications connection (either hardwired, wireless, or a combinationof hardwired or wireless) to a computer, hardwired devices for sendingand receiving computer-executable instructions, data structures, and/ordata signals (e.g., wires, cables, optical fibers, electronic circuitry,chemical, and the like) should properly be viewed as physicalcomputer-readable mediums while wireless carriers or wireless mediumsfor sending and/or receiving computer-executable instructions, datastructures, and/or data signals (e.g., radio communications, satellitecommunications, infrared communications, and the like) should properlybe viewed as intangible computer-readable mediums. Combinations of theabove should also be included within the scope of computer-readablemedia.

Computer-executable instructions include, for example, instructions,data, and/or data signals which cause a general purpose computer,special purpose computer, or special purpose processing device toperform a certain function or group of functions. Although not required,aspects of the invention have been described herein in the generalcontext of computer-executable instructions, such as program modules,being executed by computers, in network environments and/or non-networkenvironments. Generally, program modules include routines, programs,objects, components, and content structures that perform particulartasks or implement particular abstract content types.Computer-executable instructions, associated content structures, andprogram modules represent examples of program code for executing aspectsof the methods disclosed herein.

Embodiments may also include computer program products for use in thesystems of the present invention, the computer program product having aphysical computer-readable medium having computer readable program codestored thereon, the computer readable program code comprising computerexecutable instructions that, when executed by a processor, cause thesystem to perform the methods of the present invention.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed is:
 1. An interface alteration device configured to beplaced between a first segment and a second segment of a communicationline of a vehicle, the interface alteration device comprising: atransceiver configured to establish a wireless data link between theinterface alteration device and a second interface alteration device soas to wirelessly transmit and receive data to and from the secondinterface alteration device; a first port configured to receive anincoming data stream from the first segment of the communication line,the incoming data stream entering with a signal protocol; an interfacealteration processor configured to: identify portions of the incomingdata stream that are to be transmitted to the second interfacealteration device and cause the identified portions to be transmitted tothe second interface alteration device by the transceiver; identifyportions of the incoming data stream that are to be replaced by datareceived over the data link from the second interface alteration device;and generate an outgoing data stream that is a replicate of the incomingdata stream except that the portions of the incoming data streamidentified to be replaced are replaced with the corresponding datareceived from the second interface alteration device; a second portconfigured to transmit the outgoing data stream onto the second segmentof the communication line at a point in time after the incoming datastream is received at the first port that is less than or equal to atotal allowed delay of the signal protocol.
 2. A system comprising: afirst interface alteration device as recited in claim 1; and a secondinterface alteration device as recited in claim 1, a wireless data linkbeing established between the first and second interface alterationdevices via the respective transceivers of the first and secondinterface alteration devices; wherein the portions of the incoming datastream identified to be transmitted by the interface alterationprocessor of the first interface alteration device and transmitted bythe transceiver of the first interface alteration device are configuredto comprise control inputs; wherein the transceiver of the secondinterface alteration device is configured to receive the control inputstransmitted by the first interface alteration device; wherein theportions identified to be replaced of the incoming data stream of thesecond interface alteration device are configured to comprise controlinputs such that the control inputs of the second interface alterationdevice are replaced with the received control inputs of the firstinterface alteration device in the outgoing data stream of the secondinterface alteration device.
 3. The system recited in claim 2, whereinthe control inputs transmitted from the first interface alterationdevice to the second interface alteration device are control inputsgenerated by a pilot.
 4. The system recited in claim 2, wherein thefirst interface alteration device is positioned in a proxy vehicle andthe second interface alteration device is positioned in a remote vehiclesuch that the remote vehicle is controllable by the proxy vehiclethrough the first and second interface alteration devices.
 5. The systemrecited in claim 4 wherein the remote vehicle is controllable by a pilotpositioned in the proxy vehicle.
 6. The system recited in claim 4,wherein the remote vehicle and the proxy vehicle are aircraft.
 7. Thesystem recited in claim 2, wherein the portions of the incoming datastream identified to be transmitted by the interface alterationprocessor of the second interface alteration device and transmitted bythe transceiver of the second interface alteration device are configuredto comprise monitoring outputs at the second interface alterationdevice; wherein the transceiver of the first interface alteration deviceis configured to receive the monitoring outputs transmitted by thesecond interface alteration device; and wherein the portions identifiedto be replaced of the incoming data stream of the first interfacealteration device are configured to comprise monitoring outputs suchthat the monitoring outputs of the first interface alteration device arereplaced with the received monitoring outputs of the second interfacealteration device in the outgoing data stream of the first interfacealteration device.
 8. A method of controlling a remote vehicle from aproxy vehicle comprising: establishing a wireless data link between afirst interface alteration device in a proxy vehicle and a secondinterface alteration device in a remote vehicle; at the first interfacealteration device: at a first initial time, receiving a first incomingdata stream from a first segment of a communication line of the proxyvehicle using a signal protocol, determining a first portion of thefirst incoming data stream to be transmitted to the second interfacealteration device; transmitting the first portion to the secondinterface alteration device using the wireless data link; at the secondinterface alteration device: receiving the first portion from the firstinterface alteration device; at a second initial time, receiving asecond incoming data stream from a first segment of a communication lineof the remote vehicle using the signal protocol; determining a secondportion of the second incoming data stream to be replaced by the firstportion received from the first interface alteration device;transmitting a first outgoing data stream onto a second segment of thecommunication line of the remote vehicle, the first outgoing data streambeing a replicate of the second incoming data stream except that thesecond portion is replaced with the first portion received from thefirst interface alteration device. wherein the first outgoing datastream is transmitted at a point in time after the second initial timethat is less than or equal to a total allowed delay associated with thesignal protocol.
 9. The method recited in claim 8, wherein the first andsecond portions comprise vehicle control inputs.
 10. The method recitedin claim 9, wherein the vehicle control inputs are generated by actionsof a pilot in the proxy vehicle.
 11. The method recited in claim 8,wherein determining the first portion of the first incoming data streamcomprises: identifying an evaluation portion of the first incoming datastream based on the signal protocol; and analyzing the evaluationportion of the first incoming data stream to determine the firstportion.
 12. The method recited in claim 8, wherein determining thesecond portion of the second incoming data stream comprises: identifyingan evaluation portion of the second incoming data stream based on thesignal protocol; and analyzing the evaluation portion of the secondincoming data stream to determine the second portion.
 13. The methodrecited in claim 12, wherein the transmission of the first outgoing datastream on the second segment of the communication line of the remotevehicle is started before the evaluation portion of the second incomingdata stream has been completely received on the first segment of thecommunication line of the remote vehicle.
 14. The method recited inclaim 8, further comprising: at the first interface alteration device:generating altered data for the first portion of the first incoming datastream; and transmitting a second outgoing data stream onto a secondsegment of the communication line of the proxy vehicle, the secondoutgoing data stream being a replicate of the first incoming data streamexcept that the first portion is replaced with the corresponding altereddata. wherein the second outgoing data stream is transmitted at a pointin time after the first initial time that is less than or equal to thetotal allowed delay associated with the signal protocol.
 15. The methodrecited in claim 8, further comprising: at the second interfacealteration device: receiving a third incoming data stream from the firstsegment of the communication line of the proxy vehicle using the signalprotocol, determining a third portion of the third incoming data streamto be transmitted to the first interface alteration device; transmittingthe third portion to the first interface alteration device using thewireless data link; at the first interface alteration device: receivingthe third portion from the second interface alteration device; at asecond initial time, receiving a fourth incoming data stream from thefirst segment of the communication line of the proxy vehicle using thesignal protocol; determining a fourth portion of the fourth incomingdata stream to be replaced by the third portion received from the secondinterface alteration device; transmitting a second outgoing data streamonto a second segment of the communication line of the proxy vehicle,the second outgoing data stream being a replicate of the fourth incomingdata stream except that the fourth portion is replaced with the thirdportion received from the second interface alteration device. whereinthe second outgoing data stream is transmitted at a point in time afterthe second initial time that is less than or equal to the total alloweddelay associated with the signal protocol.
 16. The method recited inclaim 15, wherein the third and fourth portions comprise vehiclemonitoring outputs.
 17. The method recited in claim 8, wherein theremote vehicle and the proxy vehicle are aircraft.